Just unexpected
by LaReinedesNieges
Summary: Senku and Koharku felt a chill down their spines and slowly turned towards the door. A deep blush began to burn.
1. Chapter 1

**Just… unexpected**

**Hello there, I'm LaReinedesNieges and this is my first story for one of my favorite animes. I'm not an expert in writing nor english. However, I'm trying to do my best. The writers of the stories that I have read so far for Senku and Kohaku are just amazing, and I wanted to contribute. I hope to deliver something that you will like.**

**If you see any mistakes on my grammar or anything, please let me know. I apologize if the characters are not as **_**in-character**_** as I would like, but I had a lot of fun writing it; so, I like it this way. **

**Also, I may warn you that I have not read the manga. This is entirely based on what I have seen on the anime and few things that I have been spoiled about. For what I'm about to write I don't know if I'm giving additional spoilers.**

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_**Dr. Stone is not of my property, it belongs to Riichiro Inagaki and Boichi.**_

* * *

**Chapter 1**

There was no way to describe it, it was just so unexpected. No one in the village saw it coming. Not even the great detective Suika.

But really, you need to cut them some slack, it was so difficult to see it at first and it escalated slow.

At first, Kohaku started to help Senku more with personal projects, like making soap or more comfortable beds for the village. She would help him with the hard work on the steps that required more stamina, strength and speed. Basically, all the traits that implied his lack of condition.

– Come on, Senku. I know that I can do this –, her patience was starting to get thin.

– It will take a lot of precious time. Not happening, lioness –, the nickname only made it a little worst.

– Really, Senku? We both know that Chrome isn't enough sometimes.

To be honest, Senku did know that this was the best thing they could do. Two heads weren't enough in this stone age. Kohaku had demonstrated that she had a quick mind and was determined as hell. All that is needed in science. The tough of teaching her had come to his mind months ago and was planning to do it in the near future, why not now if she was willing?

Knowing this, why was he saying no? Well… he wanted to see a little bit of begging.

– If you don't want to waste much time, it can be during the nights… a couple of hours a day, that is all I'm asking for. I can come to your laboratory and… –.

– Fine, we start tonight but I will hear no complains. You complain and I'm done –, he cut her rambling.

– Are you serious? –, her mouth was wide open.

– Ten billion percent serious -, Senku assured while digging in his ear.

– Won't let you down – said with a bright smile leaving his laboratory.

_Well this is going to be tough_ Senku though as he continued with his plans.

**-o-o-o-**

– What is the matter? Cat got your tongue? –, he couldn't suppress a smirk.

– What cat? Is this supposed to be a cat? You are the worst drawer ever. There is no way this figures that you made are a cat! –, she watched with blinking the ground.

– This is going to be a long and painful –, he had forgotten that she couldn't read, not even her name.

* * *

Those hours each night was the beginning. It took a few months for them to get closer.

Senku didn't notice when her spontaneous touches didn't bother him anymore, even less when he started to touch her too in a more casual way. Once her learning was over – which was only until middle school, _she didn't need more_, according to him – the late nights in the lab didn't come to an end.

– Senku… are you sure this is… normal?… in your time… –, the blond could barely say between kisses.

– What is the matter, lioness? Do you want me to stop? –, his hands were moving from her wide hips to her slim waist – I already told you…

– Yeah, yeah, yeah… a ten billion times. I don't need that lecture of our primitive ways another time –, her legs were now wrapped around his waist.

– Then don't ask for it again –, Senku was grateful that she was sitting on the table. He didn't have enough force to lift her if her feet aren't on the ground.

– Shut up… –, those were the last words spoken for the night as Senku led her to lay on the table as he introduced his tongue in the blond's mouth.

Soon, nights weren't enough.

.

As Senku was planning to build the furnaces in every home, he sent Chrome to find more metals with Magma and Ruri, at her insistence to be helpful. Everything was going smoothly to make the telephone; all the village was helping after all. To think that it all began with four persons in the very beginning of the Kingdom of Science.

He began to distract himself with the sounds of Kohaku's hammer as she was refining some copper outside the lab. Senku stared at her as she swiped some sweat out of her brow, but he quickly turns away as the blond stood up and entered holding the copper.

– Done –, she said with a proud smile.

A growl was all she received as response. Senku seemed to be very busy looking at the plans before him, she peeked above his shoulder supporting her chin in his shoulder. Unconsciously, he rested his head above hers, making simple calculations to determine the time it would take to construct one furnace in each home.

It was rare this kind of moments, were the two of them acted on their feelings… well, _feelings_.

It is impossible be that near each other without making a more intimate contact. It was matter of minutes before they were kissing. Well if you can call that a kiss, Senku blamed the hormones as he strokes Kohaku's leg that is up to his hip.

– Senku, we are sorry to bother you, but we were wondering if… –, the words were drowned in Ruri's throat. She and Chrome turned back to ask something about the cave, and they found quite a scene after moving aside the mantel that worked as door in the lab.

Senku and Koharku felt a chill on their spines and slowly turned towards the door. A deep blush began to burn in Kohaku and Ruri's faces.

– Nevermind! –, Chrome was the first one to react closing the door with the mantel.

Well, that was new.

.

Ruri and Chrome didn't touch the subject until they were back in the cave. While Magma was extracting some minerals with a pickaxe, they were searching in the surroundings for more rocks.

– I had no idea they were together –, Ruri was the first one to talk about the elephant in the room.

– I had no idea Senku was even interested into that! – Chrome was still shocked.

– Did he ever mention anything? –.

– No… did Kohaku tell you something? –.

– No…

They remained silent as Magma approached again, once he began to work again and they were far enough they continued with the topic.

– Well, I never excepted the day would come when Kohaku had a boyfriend –, Ruri let out a nervous smile.

– Wait… are they together? – Chrome turned to look at her.

– You don't think they are together?

– This is Senku and the go… and Kohaku we are talking about –, he corrected himself at Ruri's gaze on him.

– I guess you are right –, she turns to the floor nodding.

– It's obvious that nobody knows besides us.

– We should keep it that way in the meanwhile, I mean… that is very private thing –, a blush was starting to creep into her cheeks again.

– Y-Yeah…

Several minutes passed with both blushed. Slowly a frown formed in Chrome's face and latter it changed to an embarrassed look.

– I… I don't know about you, but I'm a little bit curious –, he glanced at Ruri.

– Oh thank God, me too! –, Ruri let out a sigh of relieve – I think our best option to know what is going on is asking my sister –.

– Yeah, let's try that first.

Magma, Chrome and Ruri left the cage a couple hours before it went dark; the latest two with a new determination on their minds.

.

At the campfire, where everyone reunited for dinner, Ruri asked her sister to keep her company for the night with the excuse of some _sister quality time_. Kohaku nodded with a smile as she got up and followed the priestess to her house. Chrome noticed how she tapped Senku's shoulder two times as the sisters passed by.

Now, this is interesting.

.

Kohaku was almost ten billion sure that her sister wanted to talk about what happened earlier in the morning. Dammit, she was starting to sound like him. Kohaku started to ask Ruri about her day and her visit to the cave.

Being honest, she wasn't exactly paying attention to her sister. The warrior was sharpening her weapons lost in thought when she noticed that Ruri stopped talking and was staring at her.

– What? –, she should have payed more attention.

– Nothing… don't worry – the priestess smiled at her returning to her sewing.

– I'm sorry.

Kohaku looked through the door to see a pitch-black sky, it was getting very late. Maybe she should go.

– Ruri, maybe I should… –, she was suddenly interrupted.

– Are you and Senku together?

– What?! –, Kohaku knew this was coming, but still the nervousness was doing its thing.

– Kohaku… I would really love if we talked about this… please –, Ruri pleaded.

Ruri was the one to win the staring contest as Kohaku turned her head away and let out a low "fine".

– Are you… –, the priestess was a little embarrassed of her question – just kissing or are you…? –, Kohaku's face turned as red as a tomato.

– Ruri!

– I'm sorry! I'm sorry! Probably not the best first question… Amm, when did this happened? –, Ruri came a little bit closer to her sister.

– After… I finished my schooling –, Kohaku was starting to play with the dirt.

– Wait… I thought you were still learning –, Ruri's voice rose a little bit – when did you finished? –.

– Six months ago…

– Six months ago!? –, Kohaku alarmed at Ruri's scream.

– Shhh! –, was the only response Kohaku could manage.

– Kohaku… –, the mentioned turned to see the priestess with a serious face.

– Do you love him?

– I…

* * *

– What did you find out? –, he said whispering.

– Well… this has been going on for six months, at first this was only during the nights… but she told me this has starting to happen sometimes in the day…

– You mean that… they are having…?

– I think… I think they do, but she didn't exactly tell me "yes".

– I can probably get a confirmation from Senku… anything else? –, Chrome peeked to see if anybody else had woken up.

– I found out my sister's feelings about the matter… It's just, I can't… –, she was cut when Chrome held her hands with a comprehensive look.

– You don't have to tell me… I understand –, he showed a tender smile.

– Thank you –, Ruri smiled with her hearth pounding.

– I will try to talk to Senku today, let's see what I can find out –, with a nod, they both left the back of the priestess house just as the sun was rising.

.

Of course, _today_ became a week.

Chrome was waiting for a chance to be alone with Senku. How the gorilla managed to be alone with him?! He was always with Kaseki, Ginro, Kinro, little Suika or the gorilla, of course.

Finally, one day most of the village went hunting for the winter and the others were helping Kaseki to strengthen the bridge. The perfect chance on a stone platter.

– Hey, Seku… can we talk? –, Chrome made sure to close the door of the lab.

– Yeah, I'm almost finished –, answered the green-haired as he was smashing something in his mortar.

– I had no idea that you and Kohaku were a thing now? –, he sits down at his side. He cursed, _I made it sound like a statement and not a question_.

– Ah? You got it all wrong… we are not a thing –, he smirked at the mortar.

– Senku… are you dishonoring the gorilla? –, Chrome frowned resting his arms on the table.

– Dishonoring?... Oh yeah, the primitive mentality… We are having sex, if that is what you are asking –, he turned from Chrome to clean the mortar. Senku found something good.

– Senku, the rest won't care you are the village chief, they are going to kill you –, stated.

– I have you to know that in the civilization, those primitive principles such as dishonoring a woman before marriage are long gone… more than a half people that have sex are just for pleasure and they do it without being married –, Chrome had to bit his tongue to avoid asking more about Senku's time, it was not the time.

– Well, that doesn't work here… they are going to kill you no matter how much you explain that to them –.

– And that is not their business… I hadn't done anything wrong, since the lioness is willing –, Chrome didn't say anything after that.

The subject seemed over when Chrome asked something that made his mind slow down.

– A brain filled with love is most illogical –, Senku stated turning focusing only on the man in front of him.

– That doesn't mean that your brain will always win to your…

– Just because I'm having sex with her doesn't mean I love her –, Senku replied hastily before Chrome could finish.

As those words left Senku's mouth, they both heard the rest of the village come from the hunting. In matter of seconds, Ruri entered the lab with a smile.

– Hey guys, Kohaku and Kinro hunted a giant boar, the village is celebrating tonight for the best hunting of all year, come on! –, she disappeared after that.

– We better go –, Chrome put his hand in the scientist's shoulder.

– I'll catch up later –, Senku said a little bit colder without looking at Chrome.

– See you later then… –, he didn't get a response.

.

Gen managed to get more than five barrels of sake for the celebration, of course, everyone was drunk enough not to notice the absence of the chief. Well, everyone except for 3 persons. A priestess, her accomplice and a certain mentalist. The latter observed with attention how Kohaku entered to the lab, he showed a little smirk opening another bottle of his precious cola.

– Senku! You are not hungry? –, Kohaku neared seeing him breaking another test tube.

– Not really –, he said without looking at the blond.

– Well… I just wanted to tell you that we can't do anything tonight… I'm feeling a little bit odd… –, she said tangling her arms in his neck and resting her head beside his.

– Fine for me. I have things to do, lioness –, the way he said the nickname this time was very different from the last months.

_Something was wrong_ Kohaku thought as she returned to the campfire; and she is determined to know why.

The moment Kohaku crossed the door, Senku turned to see her go. His eyes didn't leave her until she was out of his sight.

– Fuck.

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**-o-o-o-**

**This turned out to be longer than what I have expected. I hope you enjoyed it. **

**Chapter one of "Just… unexpected" was finished on 12/29/2019. 2,435 words.**

**Last edition on 12/31/2019. 2,443 words.**

**LaReinedesNieges.**


	2. Chapter 2

**Just… unexpected**

**Hi there, I'm back, I little bit late but still here. I had very busy days so I couldn't write much. I hope you enjoy this chapter as well. I thank all the users that left a review, it made me very happy to see that you are enjoying this as much as I do. Thank you.**

**I really don't know why I always end up writing things like this. Warning: explicit content.**

**As always, do tell if you see any grammar mistakes.**

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_**Dr. Stone is not of my property, it belongs to Riichiro Inagaki and Boichi.**_

* * *

**Chapter 2**

The day after the party, Chrome couldn't get a chance to talk to Senku. He was almost lashing everyone to progress with the Kingdom of Science, murmuring about how they had lost so much time on the last weeks.

Chrome wasn't against it, the scientist didn't seem that angry against him anymore. Well who could be angry when they were doing their precious science? Nevertheless, he and Ruri were watching Senku and the gorilla carefully.

Ha! They weren't expecting what came next.

.

By the time Chrome got to the ex-chief's house, Ruri was already sitting in the floor with her father.

– Sit down – Kokuyo said with a calmed tone. Ruri gave him a confused look as he sat down.

– Father, why are we here? – the scientist-to-be nodded to say he agreed with her.

– I believe you, kids, know perfectly why you are here – the man tensed the _why_ part. As he saw their confusion faces, he proceeded – the whole village has noticed how you two stick like leeches to each other.

– But…

– No but's, I have seen this by my own and the guards have saw it too. There is no point in trying to deny it – Kokuyo turned to see Chrome with a stoic expression – and I thought that of all the men in this village, you were the one that wasn't going to disappoint me.

_What?! I'm the one disappointing him?! For freaking Pete's sake, I'm not the one dishonoring one of his daughters! And the guards?! Sure! They notice them talking for the last few days, but they don't notice the pair of bunnies at the lab?!_

– You are mistaken, father… we… – Ruri was cut by the man with a gesture of his hand.

– I man must accept his actions, my child… you will have your turn once he explains himself. – he continued to scold Chrome – a man with honor would come to me if he wants to court my daughter – Ruri showed a deep blush while Chrome was clenching his fist on his lap.

– I'm not courting your daughter – Chrome faced the man with determination – we are just friends –.

– You are no longer kids! I was a young man too and not once in my life I did such a humiliation to a lass.

– I would never dishonor your daughter! We are doing something – Chrome wanted to slap himself the moment those words left his mouth.

– _Something_?

This was getting to dangerous territory.

– Yes, it's for Senku – Ruri chirped in.

_Well, we are not lying._

– What kind of _something_? – Kokuyo looked at both teens.

_There it goes the "not lying"._

– I was helping Ruri to write the hundredth stories – Chrome cursed mentally, his voice came a little bit more acute.

– Yes! Chrome is the only one in the village that can write besides Senku… and Kohaku is still learning…

_Sure, she was learning all right_ thought Chrome full of annoyance.

– Something about memory not been reliable – the brown-haired mentioned with a memory rolling of Senku scolding him for remembering the information and not writing it.

– I see… – the man listened with understanding – I must apologize to you, I doubted of your honor –.

– Please, father… don't apologize – Ruri felt remorse for lying to him, but their mission was bound to be a secret.

– Yes, we should have told you, to avoid misunderstandings like this – Chrome assured.

– I'll let you two continue – Kokuyo said with a smile as he exited the house.

The two teenagers left out a big sigh.

– I really feel bad for lying to my father – Ruri looks at the ground with a sad expression.

– Me too… and I feel worst because now we have more work to do – he could already imagine the pain in his hands for writing.

* * *

Senku felt the exhaustion the moment his back touched the bed alongside the panting blond. However, that didn't last long. Kohaku was up, and she was sitting above him. Her eyes showed the same shine after they were together.

– Wait, lioness… I need time to recover – the green-haired closed his eyes trying to catch his breath.

– No… – she gulped – you have been acting weird this last days…– Senku noticed how Kohaku placed her hands in his chest, avoiding any scape.

_Like I could move her after this._

– What about it?

– I want to know why.

– It's something stupid Chrome said. Nothing you should be worried about, lioness – he tried to stand up. He rested against the wall crossing his arms with the woman still few inches away.

– I'm not buying it. Not after you told me that it's stupid I was worried over getting pregnant for this.

– I check your cervical mucus every day and I keep a record. You are not on your fertile days. You won't get pregnant. – Senku explained letting out a snort.

_Definitely not an accurate method. Not even close. But with the resources we have at the moment, the symptothermal method is the best we can have. _

– Well that is nice, but you haven't answered – Kohaku crossed her arms just below her still naked breasts. Senku's gaze went there for a few seconds before landing on her frowned face.

– I don't see why you want to know.

– Are you challenging me? – the blond's eyes sharpened.

– I am, lioness – Senku dared with a devious smirk knowing that she wouldn't harm him.

The green-haired clenched his teeth. Kohaku started to swing her hips making their cores touch. Her wet folds were grapping part of his wakening cock. Lost in his own sensations, Senku missed to see how she was suppressing moans.

– You better start talking, or I'll make you say it with other methods – finally, she stopped her movements.

– You forget that this said methods can also make you shut up – Kohaku let out a high moan with her eyes wide when she felt him enter him with a sneaky movement of his hips and hands.

With her lack of concentration, Senku took advantage and made her fall in the bed again positioning himself on top. However, her hands were faster and stopped him by the chest. They were both gasping for air looking into each other's eyes.

He felt in a second how he exited of her core and by the next, Kohaku was caressing his cock with her soft hand.

– Start talking.

The scientist saw his chance and took it. Senku knew every time he kissed her, her hands would go to his hair and she would press her breast against him. She did it almost as a reflex. Hence, he smashed his lips against hers.

Feeling her hands in place, he put the cherry on top of the cake. Senku found her clitoris and started rubbing it fast. Kohaku lost in matter of minutes. She moaned high and hard his name supporting herself of him the moment she came in his hand. Senku smirked as he saw her legs shiver.

His mental victory didn't last long. He totally underestimated her stamina and strength. Kohaku pushed him and he fell with a loud thud in the bed again. She was careful to sit on top of his stomach, clearly, she was supporting herself with her knees. His hands were prisoned by hers on each side of his head.

– Now, this is playing dirty, lioness… – Senku knew he was at her total mercy.

– I'll let you go if you tell me.

– No.

– Why not?!

– Because!

– Then say goodbye to your precious science, you are not leaving this bed.

Senku arched an eyebrow and showed a smirk. Kohaku turned red when she heard in her head what she said.

– You know what I mean, you pervert! – her grip became softer.

– Says the one who's naked on top of the other – the scientist mocked.

– Tell me!

– You want the truth?! – he was starting to lose his temper.

– For someone so smart, took you long enough to get it!

– I. Love. You!

* * *

Chrome and Kaseki were building the furnaces now that the plans were finished. They were a step closer to finish the telephone! What ever the hell was that! But it sure sounded cool!

Only half of the houses were missing. At this rate, they would finish by tomorrow morning and now the kids and Ruri wouldn't get cold as they were making the copper cables.

_Today was a good day_, Chrome thought smiling before remembering that he and Ruri were barely at story number 10. _That's what we get for lying_, said Ruri with defeat the day they started writing.

.

– The gorilla sure is happy today – the brown-haired mentioned to Ruri munching his food.

– Yeah… I don't think I've seen her like this in all my life – the priestess smiled seeing her sister eat happily talking to their father.

Chrome was about to answer when he felt how someone smacked him at the back of his head.

– What was that for?! – he turned.

– You better be happy – Senku barely said taking seat at his side.

– What? What for? – Chrome frowned.

– I talked to the lioness.

– Oh great! That's great!

Chrome and Ruri smacked their hands in a high five with a cry of victory.

– Oh shut up! It's not that big of a deal – Senku grabbed a cup of what it seemed like water.

However, the rest of the village that was at the campfire got curious at the gesture of Chrome and Ruri.

– My… my… what are we celebrating? – Gen asked with a wicked smile.

– Senku and my sister are getting married! – Ruri could barely contain her happiness.

At those words, Kohaku spitted the food that was seconds ago in her mouth and Senku also spitted his drink in Kokuyo's face.

– Senku! – Kohaku looked in disbelief at him.

– What?! Don't look at me like that! I never said such a ridiculous thing! – Senku claimed.

– What? But I thought since you were… – Ruri looked confused both.

– They are what? – Kokuyo sounded very angry. Furious.

– Ah? We are having sex – the soon to be death said digging in his ear with indifference.

* * *

**-o-o-o-**

**Chapter two of "Just… unexpected" was finished on 01/08/2020. 1,680 words.**

**Last edition on 01/08/2020. 1,677 words.**

**LaReinedesNieges.**


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